diff --git a/packages/router-generator/src/utils.ts b/packages/router-generator/src/utils.ts
index 9fa8d229a4..1f00d37999 100644
--- a/packages/router-generator/src/utils.ts
+++ b/packages/router-generator/src/utils.ts
@@ -19,6 +19,19 @@ export class RoutePrefixMap {
     for (const route of routes) {
       if (!route.routePath || route.routePath === `/${rootPathId}`) continue
 
+      // Skip route pieces (lazy, loader, component, etc.) - they are merged with main routes
+      // and should not be valid parent candidates
+      if (
+        route._fsRouteType === 'lazy' ||
+        route._fsRouteType === 'loader' ||
+        route._fsRouteType === 'component' ||
+        route._fsRouteType === 'pendingComponent' ||
+        route._fsRouteType === 'errorComponent' ||
+        route._fsRouteType === 'notFoundComponent'
+      ) {
+        continue
+      }
+
       // Index by exact path for direct lookups
       this.prefixToRoute.set(route.routePath, route)
 
diff --git a/packages/router-generator/tests/generator/lazy/routeTree.snapshot.ts b/packages/router-generator/tests/generator/lazy/routeTree.snapshot.ts
new file mode 100644
index 0000000000..ea40f442ad
--- /dev/null
+++ b/packages/router-generator/tests/generator/lazy/routeTree.snapshot.ts
@@ -0,0 +1,104 @@
+/* eslint-disable */
+
+// @ts-nocheck
+
+// noinspection JSUnusedGlobalSymbols
+
+// This file was automatically generated by TanStack Router.
+// You should NOT make any changes in this file as it will be overwritten.
+// Additionally, you should also exclude this file from your linter and/or formatter to prevent it from being checked or modified.
+
+import { Route as rootRouteImport } from './routes/__root'
+import { Route as PostsRouteRouteImport } from './routes/posts.route'
+import { Route as PostsIndexRouteImport } from './routes/posts.index'
+import { Route as PostsPostIdRouteImport } from './routes/posts.$postId'
+
+const PostsRouteRoute = PostsRouteRouteImport.update({
+  id: '/posts',
+  path: '/posts',
+  getParentRoute: () => rootRouteImport,
+} as any).lazy(() => import('./routes/posts.route.lazy').then((d) => d.Route))
+const PostsIndexRoute = PostsIndexRouteImport.update({
+  id: '/',
+  path: '/',
+  getParentRoute: () => PostsRouteRoute,
+} as any)
+const PostsPostIdRoute = PostsPostIdRouteImport.update({
+  id: '/$postId',
+  path: '/$postId',
+  getParentRoute: () => PostsRouteRoute,
+} as any)
+
+export interface FileRoutesByFullPath {
+  '/posts': typeof PostsRouteRouteWithChildren
+  '/posts/$postId': typeof PostsPostIdRoute
+  '/posts/': typeof PostsIndexRoute
+}
+export interface FileRoutesByTo {
+  '/posts/$postId': typeof PostsPostIdRoute
+  '/posts': typeof PostsIndexRoute
+}
+export interface FileRoutesById {
+  __root__: typeof rootRouteImport
+  '/posts': typeof PostsRouteRouteWithChildren
+  '/posts/$postId': typeof PostsPostIdRoute
+  '/posts/': typeof PostsIndexRoute
+}
+export interface FileRouteTypes {
+  fileRoutesByFullPath: FileRoutesByFullPath
+  fullPaths: '/posts' | '/posts/$postId' | '/posts/'
+  fileRoutesByTo: FileRoutesByTo
+  to: '/posts/$postId' | '/posts'
+  id: '__root__' | '/posts' | '/posts/$postId' | '/posts/'
+  fileRoutesById: FileRoutesById
+}
+export interface RootRouteChildren {
+  PostsRouteRoute: typeof PostsRouteRouteWithChildren
+}
+
+declare module '@tanstack/react-router' {
+  interface FileRoutesByPath {
+    '/posts': {
+      id: '/posts'
+      path: '/posts'
+      fullPath: '/posts'
+      preLoaderRoute: typeof PostsRouteRouteImport
+      parentRoute: typeof rootRouteImport
+    }
+    '/posts/': {
+      id: '/posts/'
+      path: '/'
+      fullPath: '/posts/'
+      preLoaderRoute: typeof PostsIndexRouteImport
+      parentRoute: typeof PostsRouteRoute
+    }
+    '/posts/$postId': {
+      id: '/posts/$postId'
+      path: '/$postId'
+      fullPath: '/posts/$postId'
+      preLoaderRoute: typeof PostsPostIdRouteImport
+      parentRoute: typeof PostsRouteRoute
+    }
+  }
+}
+
+interface PostsRouteRouteChildren {
+  PostsPostIdRoute: typeof PostsPostIdRoute
+  PostsIndexRoute: typeof PostsIndexRoute
+}
+
+const PostsRouteRouteChildren: PostsRouteRouteChildren = {
+  PostsPostIdRoute: PostsPostIdRoute,
+  PostsIndexRoute: PostsIndexRoute,
+}
+
+const PostsRouteRouteWithChildren = PostsRouteRoute._addFileChildren(
+  PostsRouteRouteChildren,
+)
+
+const rootRouteChildren: RootRouteChildren = {
+  PostsRouteRoute: PostsRouteRouteWithChildren,
+}
+export const routeTree = rootRouteImport
+  ._addFileChildren(rootRouteChildren)
+  ._addFileTypes<FileRouteTypes>()
diff --git a/packages/router-generator/tests/generator/lazy/routes/__root.tsx b/packages/router-generator/tests/generator/lazy/routes/__root.tsx
new file mode 100644
index 0000000000..3797d7bf8c
--- /dev/null
+++ b/packages/router-generator/tests/generator/lazy/routes/__root.tsx
@@ -0,0 +1,15 @@
+import * as React from 'react'
+import { Outlet, createRootRoute } from '@tanstack/react-router'
+
+export const Route = createRootRoute({
+  component: RootComponent,
+})
+
+function RootComponent() {
+  return (
+    <React.Fragment>
+      <div>Hello "__root"!</div>
+      <Outlet />
+    </React.Fragment>
+  )
+}
diff --git a/packages/router-generator/tests/generator/lazy/routes/posts.$postId.tsx b/packages/router-generator/tests/generator/lazy/routes/posts.$postId.tsx
new file mode 100644
index 0000000000..8782ec97d8
--- /dev/null
+++ b/packages/router-generator/tests/generator/lazy/routes/posts.$postId.tsx
@@ -0,0 +1,9 @@
+import { createFileRoute } from '@tanstack/react-router'
+
+export const Route = createFileRoute('/posts/$postId')({
+  component: RouteComponent,
+})
+
+function RouteComponent() {
+  return <div>Hello "/posts/$postId"!</div>
+}
diff --git a/packages/router-generator/tests/generator/lazy/routes/posts.index.tsx b/packages/router-generator/tests/generator/lazy/routes/posts.index.tsx
new file mode 100644
index 0000000000..edd51af264
--- /dev/null
+++ b/packages/router-generator/tests/generator/lazy/routes/posts.index.tsx
@@ -0,0 +1,9 @@
+import { createFileRoute } from '@tanstack/react-router'
+
+export const Route = createFileRoute('/posts/')({
+  component: RouteComponent,
+})
+
+function RouteComponent() {
+  return <div>Hello "/posts/"!</div>
+}
diff --git a/packages/router-generator/tests/generator/lazy/routes/posts.route.lazy.tsx b/packages/router-generator/tests/generator/lazy/routes/posts.route.lazy.tsx
new file mode 100644
index 0000000000..906c2167dc
--- /dev/null
+++ b/packages/router-generator/tests/generator/lazy/routes/posts.route.lazy.tsx
@@ -0,0 +1,9 @@
+import { createLazyFileRoute } from '@tanstack/react-router'
+
+export const Route = createLazyFileRoute('/posts')({
+  component: RouteComponent,
+})
+
+function RouteComponent() {
+  return <div>Hello "/posts"!</div>
+}
diff --git a/packages/router-generator/tests/generator/lazy/routes/posts.route.tsx b/packages/router-generator/tests/generator/lazy/routes/posts.route.tsx
new file mode 100644
index 0000000000..929cb15377
--- /dev/null
+++ b/packages/router-generator/tests/generator/lazy/routes/posts.route.tsx
@@ -0,0 +1,9 @@
+import { createFileRoute } from '@tanstack/react-router'
+
+export const Route = createFileRoute('/posts')({
+  component: RouteComponent,
+})
+
+function RouteComponent() {
+  return <div>Hello "/posts"!</div>
+}